Object Gripping Systems and Methods

ABSTRACT

Example systems and methods are described that are capable of gripping objects. In one implementation, a system includes a first finger that includes a plurality of teeth and a second finger that is mechanically coupled to the first finger and includes a plurality of teeth. The first finger and the second finger are configured to move apart when the first finger and the second finger are moved in a first direction against an object. The first finger and second finger are further configured to grip the object when the first finger and the second finger are moved in a second direction that is substantially opposite to the first direction.

TECHNICAL FIELD

The present disclosure relates to systems and methods that use roboticmanipulators or robotic actuators in association with grippers tomanipulate objects.

BACKGROUND

In many situations, a robotic actuator is useful for moving objectsbetween two locations. The process of automating movement of objectsbetween locations involves the need to manipulate the objects, whichincludes properly grasping or gripping an object, moving the object, andreleasing the object at a destination. In some situations, gripping anobject is difficult due to the object's placement, position, shape,weight, and so forth. In these situations, a gripper may be useful inestablishing and maintaining a strong grip on the object. There exists aneed, therefore, for an object gripping system that includes a gripperto make manipulation of the object easier by the robotic actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present disclosureare described with reference to the following figures, wherein likereference numerals refer to like parts throughout the various figuresunless otherwise specified.

FIG. 1 is a schematic diagram depicting an embodiment of an objectgripping system configured to grip and manipulate objects.

FIG. 2A is a schematic diagram depicting an isometric view of anembodiment of a passive gripper.

FIG. 2B is a schematic diagram depicting a first state in a sequence ofoperations associated with gripping an object by an embodiment of apassive gripper.

FIG. 2C is a schematic diagram depicting a second state in a sequence ofoperations associated with gripping an object by an embodiment of apassive gripper.

FIG. 2D is a schematic diagram depicting a third state in a sequence ofoperations associated with gripping an object by an embodiment of apassive gripper.

FIG. 3A is a schematic diagram depicting an isometric view of anembodiment of an active gripper.

FIG. 3B is a schematic diagram depicting a view of an embodiment of anactive gripper gripping an object.

FIG. 3C is a schematic diagram depicting a first state in a sequence ofoperations associated with gripping an object by an embodiment of anactive gripper.

FIG. 3D is a schematic diagram depicting a second state in a sequence ofoperations associated with gripping an object by an embodiment of anactive gripper.

FIG. 3E is a schematic diagram depicting a third state in a sequence ofoperations associated with gripping an object by an embodiment of anactive gripper.

FIG. 4 is a block diagram depicting an embodiment of an object grippingsystem.

FIG. 5 is a block diagram depicting an embodiment of a processing systemcapable of operating a robotic actuator and gripper configured to gripand manipulate objects.

FIG. 6 is a block diagram depicting an embodiment of a robotic actuator.

FIG. 7 is a block diagram depicting an embodiment of a sensing system.

FIGS. 8A-8F are schematic diagrams depicting a sequence of operationsassociated with gripping an object by an embodiment of a gripper.

FIGS. 9A and 9B are flow diagrams depicting an embodiment of a methodfor gripping an object by a passive gripper.

FIGS. 10A and 10B are flow diagrams depicting an embodiment of a methodfor gripping an object by an active gripper.

DETAILED DESCRIPTION

In the following disclosure, reference is made to the accompanyingdrawings, which form a part hereof, and in which is shown by way ofillustration specific implementations in which the disclosure may bepracticed. It is understood that other implementations may be utilizedand structural changes may be made without departing from the scope ofthe present disclosure. References in the specification to “oneembodiment,” “an embodiment,” “an example embodiment,” etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to affect such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described.

Implementations of the systems, devices, and methods disclosed hereinmay comprise or utilize a special purpose or general-purpose computerincluding computer hardware, such as, for example, one or moreprocessors and system memory, as discussed herein. Implementationswithin the scope of the present disclosure may also include physical andother computer-readable media for carrying or storingcomputer-executable instructions and/or data structures. Suchcomputer-readable media can be any available media that can be accessedby a general purpose or special purpose computer system.Computer-readable media that store computer-executable instructions arecomputer storage media (devices). Computer-readable media that carrycomputer-executable instructions are transmission media. Thus, by way ofexample, and not limitation, implementations of the disclosure cancomprise at least two distinctly different kinds of computer-readablemedia: computer storage media (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM,solid state drives (“SSDs”) (e.g., based on RAM), Flash memory,phase-change memory (“PCM”), other types of memory, other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store desired program code means inthe form of computer-executable instructions or data structures andwhich can be accessed by a general purpose or special purpose computer.

An implementation of the devices, systems, and methods disclosed hereinmay communicate over a computer network. A “network” is defined as oneor more data links that enable the transport of electronic data betweencomputer systems and/or modules and/or other electronic devices. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a computer, the computer properly views theconnection as a transmission medium. Transmissions media can include anetwork and/or data links, which can be used to carry desired programcode means in the form of computer-executable instructions or datastructures and which can be accessed by a general purpose or specialpurpose computer. Combinations of the above should also be includedwithin the scope of computer-readable media.

Computer-executable instructions comprise, for example, instructions anddata which, when executed at a processor, cause a general purposecomputer, special purpose computer, or special purpose processing deviceto perform a certain function or group of functions. The computerexecutable instructions may be, for example, binaries, intermediateformat instructions such as assembly language, or even source code.Although the subject matter is described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the described features or acts described herein.Rather, the described features and acts are disclosed as example formsof implementing the claims.

Those skilled in the art will appreciate that the disclosure may bepracticed in network computing environments with many types of computersystem configurations, including, an in-dash vehicle computer, personalcomputers, desktop computers, laptop computers, message processors,hand-held devices, multi-processor systems, microprocessor-based orprogrammable consumer electronics, network PCs, minicomputers, mainframecomputers, mobile telephones, PDAs, tablets, pagers, routers, switches,various storage devices, and the like. The disclosure may also bepracticed in distributed system environments where local and remotecomputer systems, which are linked (either by hardwired data links,wireless data links, or by a combination of hardwired and wireless datalinks) through a network, both perform tasks. In a distributed systemenvironment, program modules may be located in both local and remotememory storage devices.

Further, where appropriate, functions described herein can be performedin one or more of: hardware, software, firmware, digital components, oranalog components. For example, one or more application specificintegrated circuits (ASICs) can be programmed to carry out one or moreof the systems and procedures described herein. Certain terms are usedthroughout the description and claims to refer to particular systemcomponents. As one skilled in the art will appreciate, components may bereferred to by different names. This document does not intend todistinguish between components that differ in name, but not function.

It should be noted that the sensor embodiments discussed herein maycomprise computer hardware, software, firmware, or any combinationthereof to perform at least a portion of their functions. For example, asensor may include computer code configured to be executed in one ormore processors, and may include hardware logic/electrical circuitrycontrolled by the computer code. These example devices are providedherein purposes of illustration, and are not intended to be limiting.Embodiments of the present disclosure may be implemented in furthertypes of devices, as would be known to persons skilled in the relevantart(s).

At least some embodiments of the disclosure are directed to computerprogram products comprising such logic (e.g., in the form of software)stored on any computer useable medium. Such software, when executed inone or more data processing devices, causes a device to operate asdescribed herein.

The systems and methods described herein use a robotic system tomanipulate objects such as articles of dishware. In some embodiments,the robotic system includes a robot or robotic actuator, a gripper, aprocessing system, and a sensing system. The gripper is configured withtwo or more fingers, where each finger includes a plurality of teeththat are used to grip an object. The fingers are locked in a grippedposition and the object is moved from a first location to a secondlocation, where the lock on the fingers is released and the object isdeposited at the second location. The robotic system may be used to moveany type of object or item in any environment.

FIG. 1 is a schematic diagram depicting an embodiment of an objectgripping system 100 configured to grip and manipulate objects. In someembodiments, object gripping system 100 includes a robotic actuator 102that is mechanically coupled to a gripper 104. In some embodiments,gripper 104 may also be referred to as a “grasper,” and the terms “grip”and “gripping” may be used interchangeably with “grasp” and “grasping”respectively. The combination of robotic actuator 102 and gripper 104may be controlled by, for example, a processing system (not shown inFIG. 1, but described herein).

In some embodiments, gripper 104 may include a plurality of fingers(i.e., at least two fingers) 106 that are configured to wrap around orengage an object to be gripped. In particular embodiments, each finger106 may include a plurality of teeth, teeth-like structures, or hooksthat are configured to grip or engage an object in a manner similar to aratcheting device. Details of the construction of gripper 104 and theassociated gripping process are provided herein.

In some embodiments, the combination of robotic actuator 102 and gripper104 may be commanded by a processing system to grip an object 110. Inparticular embodiments, object 110 may be one of a collection of objectssuch as a stack of articles of dishware 108 that rests on a work surface112. In other embodiments, the object to be gripped may be a standaloneitem. In some embodiments, an object to be gripped by object grippingsystem 100 may include articles with peripheral rim-like edges, such asarticles of dishware, including plates and bowls, as well as objectssuch as pans, trays, wafers, flat plates, etc.

In some embodiments, the process of gripping and manipulating object 110includes the following steps:

-   -   The combination of robotic actuator 102 and gripper 104 is moved        towards object 110 to be gripped and manipulated.    -   Fingers 106 of gripper 104 wrap around object 110. In some        embodiments, each finger 106 may have a pivoted end proximate to        robotic actuator 102 and a free distal end. This arrangement        allows the fingers 106 to collectively wrap around and engage        object 110 to be gripped.    -   One or more teeth in each of the fingers 106 engage with a        feature in object 110 (e.g., a peripheral rim or edge of object        110).    -   Fingers 106 are locked by a locking mechanism that may include a        mechanical clutch—this completes the gripping process.    -   The combination of robotic actuator 102 and gripper 104 lifts        object 110—this process may generate additional gripping forces        to strengthen the grip of gripper 104 on object 110.    -   The combination of robotic actuator 102 and gripper 104        manipulates object 110 (e.g., moves object 110 from a first        location to a second location).    -   The locking mechanism is unlocked so that fingers 106 release        the grip on the object and object 110 is released.

In some embodiments, gripper 104 may be described as a passive gripperthat is configured to grip object 110 using forces generated by acombination of gravity, compliant members such as springs that are apart of the gripper, and the weight of the object. In other embodiments,gripper 104 may be described as an active gripper that is configured togrip an object using forces generated by actuators such as pneumaticpistons, electric motors, solenoids, hydraulic cylinders, or phasechange materials (such as electro-active polymers, shape memory alloy,piezoelectric actuators, etc.). Examples and operational details of bothpassive grippers and active grippers are provided herein.

In some embodiments, gripper 104 may be interchangeable from a differentgrippers, where each gripper may be configured to perform differentfunctions or grip different kinds of objects. For example, one grippermay be configured to grip and manipulate plates, while another grippermay be configured to grip and manipulate bowls. In particularembodiments, the fingers associated with gripper 104 may be removable(or replaceable) independently of other fingers associated with gripper104. For example, a finger may need to be removed for cleaning, or afinger may be worn out and may need replacing, or a finger with aspecific geometry (e.g., tooth structure) may be needed for a specificapplication.

The plurality of teeth on each finger associated with gripper 104 allowsgripper 104 to engage objects of varying sizes while allowing for agreater tolerance for error in the positioning accuracy of gripper 104with respect to an object to be gripped. In the event that the objectsare articles of dishware, the plurality of teeth allows object grippingsystem 100 to accommodate different dish sizes.

FIG. 2A is a schematic diagram depicting an isometric view of anembodiment of a passive gripper 200. In some embodiments, passivegripper 200 includes a housing 202 that contains mechanical elementsassociated with passive gripper 200, for example spring mechanisms,pivots, locking mechanisms, and rigid support structures. Thesemechanical elements serve to mechanically couple the plurality offingers associated with passive gripper 200; these mechanical elementstogether comprise what is referred to as a “mechanical coupling.” Forexample, a rigid support structure may form the basis for a rigidmechanical reference for any motion of any fingers associated withpassive gripper 200. These fingers may be configured to move around oneor more pivots. Spring mechanisms are an integral part of an embodimentof a passive gripper, as discussed herein. Locking mechanisms serve tolock one or more fingers associated with passive gripper 200 in placewhen an object is being gripped by passive gripper 200. Examples oflocking mechanisms include mechanical clutches, as discussed herein.Housing 202 also includes a mechanical coupling interface 203 thatallows passive gripper 200 to be mechanically coupled to a roboticactuator such as robotic actuator 102.

In some embodiments, passive gripper 200 may include a plurality offingers such as a finger 204, a finger 206, and a finger 208. Additionalfingers may be associated with passive gripper 200 that are not visiblein FIG. 2A as they might be concealed behind housing 202 in theisometric view presented in FIG. 2A. Each of finger 204-208 may includea plurality of teeth or teeth-like structures. For example, a tooth 212is shown on finger 204. Each of the fingers 204-208 associated withpassive gripper 200 in conjunction with the corresponding teeth isconfigured to grip an object, as discussed herein. FIG. 2A depictspassive gripper 200 gripping an object 210 (an article of dishware inthis example) using at least a combination of fingers 204-208. Object210 is shown to be gripped by each tooth associated with fingers204-208.

FIG. 2B is a schematic diagram depicting a first state 214 in a sequenceof operations associated with gripping an object by an embodiment of apassive gripper such as passive gripper 200. First state 214 depicts aportion of passive gripper 200; specifically, first state 214 depicts aportion of finger 204 along with internal components of passive gripper200 that are associated with finger 204. (These internal components aretotally or partially concealed within housing 202 in FIG. 2A.) Finger204 is configured to rotate about a pivot 220. The correspondingdirections of rotation of finger 204 are a first rotation direction 226and a second rotation direction 228. At equilibrium when finger 204 isnot involved in gripping an object, finger 204 is at a rest positionwhere the weight of finger 204 is balanced by tension in a spring 224.In this sense, spring 224 can be viewed as a spring mechanism that iscoupled to finger 204. First state 214 also depicts a roller clutch 222that is configured to lock finger 204 such that motion of finger 204 isconstrained. In first state 214, roller clutch 222 is shown to bedisengaged; finger 204 is thus able to move in either first rotationdirection 226 or second rotation direction 228 under the application ofan external force. When this external force is removed, finger 204returns to its rest position at equilibrium based on the mechanicalinteraction between the weight of finger 204 and the tension in spring224. Other fingers associated with passive gripper 200 may be associatedwith similar mechanical coupling and functionality as finger 204,including a separate spring mechanism (such as spring 224) associatedwith each finger.

In some embodiments, the fingers associated with a passive gripper suchas passive gripper 200 move independently of one another. For example, aforce applied to move finger 204 would not have any effect on finger 206or finger 208 in terms of initiating any motion in either of finger 206or finger 208. The fingers associated with passive gripper 200 are thussubject to a mechanical coupling with independent motion of the fingers.A further description of passive gripping is described herein.

FIG. 2C is a schematic diagram depicting a second state 230 in asequence of operations associated with gripping an object by anembodiment of a passive gripper such as passive gripper 200. In secondstate 230, continuing from first state 214, passive gripper 200 is shownto be in the process of gripping a portion of an object 232. The portionof object 232 is shown to be gripped by a tooth 233 associated withfinger 204; other teeth associated with other fingers also gripdifferent portions of object 232 (not depicted in second state 230).Second state 320 shows tooth 233 engaged with an edge of object 232.Roller clutch 222 is disengaged in second state 230, while spring 224exerts tension to balance the weight of finger 204 and any added forceon finger 204 due to object 232. In this sense, the tension exerted byspring 224 serves to enhance the grip exerted by finger 204 on object232. (Similar springs associated with other fingers similarly serve toenhance a grip exerted by the respective finger on object 232.) Secondstate also depicts pivot 220.

FIG. 2D is a schematic diagram depicting a third state 234 in a sequenceof operations associated with gripping an object by an embodiment of apassive griper such as passive gripper 200. Continuing from second state230, roller clutch 222 is shown to be in a locked position. Thisprevents finger 204 from moving in a blocked direction of rotation 236(originally first rotation direction 226). Finger 204 may still move insecond rotation direction 228; however a physical constraint posed byobject 232 may prevent any motion of finger 204 in second rotationdirection 228 about pivot 220 or in any other direction. In someembodiments, finger 204 and other fingers associated with passivegripper 200 can be described as self-closing, as the teeth of thefingers associated with passive gripper 200 engage under a rim of theobject to be gripped, and the associated weight of the object causes thefingers and associated teeth to increase the grip on the object. Inparticular embodiments, this is especially true when passive gripper 200is lifted by a robotic actuator such as robotic actuator 102. Thisoccurs due to the mechanical structure of passive gripper 200, toinclude fingers, teeth, and mechanical coupling components such as rigidsupports, springs, pivots and so on.

In third state 234, finger 204 is substantially locked by a combinationof roller clutch 222, the forces generated by the interaction betweentooth 233 and object 232, and the rigid structure of finger 204.Similarly, any other finger associated with object 232 are locked bysimilar independent processes as described in the sequence of firststate 214, second state 230, and third state 234. The net effect of allfingers being locked in this manner is that object 232 is gripped bypassive gripper 200. Additional gripping forces may be generated by thefingers associated with passive gripper 200 when object 232 is liftedoff of a work surface by passive gripper 200. The sequence of firststate 214, second state 230, and third state 234 illustrates a passivegripping process. In summary, a passive gripping process involves atleast two fingers and associated teeth engaging with an object to begripped and a corresponding locking mechanism to help lock the fingersin place to help enhance the strength of the grip.

FIG. 3A is a schematic diagram depicting an isometric view of anembodiment of an active gripper 300. In some embodiments, active gripper300 comprises a mechanical coupling interface 302 that allows activegripper 300 to be mechanically coupled to a robotic actuator such asrobotic actuator 102. Active gripper 300 also includes four fingers—afinger 304, a finger 306, a finger 308, and a finger 310. Each of finger304-310 is mechanically coupled to a separate pivot; for example finger304 is mechanically coupled to a pivot 315 while finger 306 ismechanically coupled to a pivot 313. Each of finger 304-310 isconfigured to rotate about its corresponding pivot upon the applicationof an external force. In some embodiments, each of finger 304-310 isconfigured with a plurality of teeth or teeth-like structures. Forexample, a tooth 317 is shown on finger 304. Each of finger 304-310 inassociation with the corresponding teeth is configured to grip anobject, as discussed herein.

In some embodiments, each of finger 304-310 is mechanically coupled to aseparate pneumatic actuator. For example, finger 304 is mechanicallycoupled to a pneumatic actuator 312, finger 306 is mechanically coupledto a pneumatic actuator 314, and finger 308 is mechanically coupled to apneumatic actuator 316. In the isometric view presented in FIG. 3A, apneumatic actuator associated with finger 310 is not visible. In someembodiments, each of pneumatic actuator 314 through pneumatic actuator316 and the pneumatic actuator associated with finger 310 ismechanically coupled to mechanical coupling interface 302. In particularembodiments, each of pneumatic actuator 314-316 and the pneumaticactuator associated with finger 310 is configured to move thecorresponding finger 304-310 respectively about its respective pivot byapplying a force to each of the fingers. Details of the operation ofactive gripper 300 are provided herein.

FIG. 3B is a schematic diagram depicting a view of an embodiment of anactive gripper such as active gripper 300 gripping an object 320. FIG.3B depicts finger 304, finger 308, pneumatic actuator 312, and pneumaticactuator 316. Object 320 is shown to be gripped by a combination of atooth 321 associated with finger 304 and a tooth 319 associated withfinger 308. All the fingers and associated mechanisms of active gripper300 collaboratively grip object 320.

FIG. 3C is a schematic diagram depicting a first state 322 in a sequenceof operations associated with gripping an object by an embodiment of anactive gripper such as active gripper 300. First state 322 depicts aportion of active gripper 300; specifically, first state 322 depicts aportion of finger 304 configured to rotate about pivot 315 in either afirst rotation direction 324 or a second rotation direction 326 under,for example, the application of a force exerted by pneumatic actuator312. In some embodiments, a degree of compliance may be built into anequilibrium state of finger 304, where some amount of spring-loadedmotion may be possible about the equilibrium state of finger 304 asdiscussed for finger 204 associated with passive gripper 200. Thediscussion applied to finger 304 and the associated portion of activegripper 300 can be extended to other fingers associated with activegripper 300. Also shown in first state 322 is a torsion spring 323 thatis configured to provide a locking force on finger 304 when an articleis gripped. Additional details of this process are provided herein. Infirst state 322, torsion spring 323 is in a free state and is neither intension or compression, and hence provides no significant force inputsto either finger 304 or any other part of active gripper 300.

FIG. 3D is a schematic diagram depicting a second state 328 in asequence of operations associated with gripping an object by anembodiment of an active gripper such as active gripper 300. In secondstate 328, continuing from first state 322, a portion of active gripper300 is in the process of gripping a portion of an object 320. Theportion of object 320 is shown to be gripped by tooth 321 associatedwith finger 304. In some embodiments, pneumatic actuator 312 may rotatefinger 304 about pivot 315 so that one or more teeth (e.g., tooth 321)engage with an edge of object 320. In second state 328, torsion spring323 is subject to some degree of compression, providing a degree ofmechanical compliance to finger 304. This mechanical compliance allowsfinger 304 to grip object 320 appropriately.

FIG. 3E is a schematic diagram depicting a third state 330 in a sequenceof operations associated with gripping an object by an embodiment of anactive gripper such as active gripper 300. Third state 330 continuesfrom second state 328. In third state 330, pneumatic actuator 312 exertsan additional force 332 on finger 304 to provide a locking effect on themechanical engagement between tooth 321 and object 320. This forcemanifests as a rotational torque 334 on finger 304 about pivot 315. Insome embodiments, rotational torque 334 bottoms out (compresses) torsionspring 323 (not shown) which, in turn, exerts a force on finger 304 thatsubstantially locks finger 304. In some embodiments, each fingerassociated with active gripper 300 may be associated with one or moretorsion springs that move independently of any torsion springsassociated with other fingers. The sequence of first state 322, secondstate 328, and third state 330 illustrates an active gripping process.

In some embodiments, active gripper 300 may include one or morecompliant members (e.g., spring-loaded mechanisms) associated with eachcombination of a finger, pivot and pneumatic actuator. These compliantmembers are not depicted in the drawings. The one or more compliantmembers limit the gripping force exerted by a gripping tooth to preventany potential damage to an object being gripped. For example, in theabsence of a compliant member if a pneumatic actuator exerts greaterthan a threshold amount of force, the resultant torque generated by afinger associated with the pneumatic actuator could be sufficient todamage or break an object being gripped (for example, an article ofdishware made of porcelain). A compliant member absorbs additional forcein excess of a threshold value via, for example, storing the excessforce as potential energy via a spring compression or a springextension, thereby preventing this excess force from being transmittedto the object being gripped and limiting the amount of force exerted onthe object being gripped. This reduces the likelihood of the objectbeing damaged by the excess force.

The discussion above for first state 322 through third state 330 can beextended to all the fingers and related mechanisms (e.g., pneumaticactuators, teeth, pivots, etc.) associated with active gripper 300 thatcollectively operate in this manner to grip an object. The grippingprocess is a collective (collaborative) effort between the differentcomponents associated with active gripper 300. During the process ofgripping an object, all fingers associated with active gripper 300 arecollectively moved to wrap around an object—in this sense the activegripping process does not involve any independent motion of the fingers.In other words, the motion of the fingers of an active gripper such asactive gripper 300 can be described as collective motion (or coupledmotion).

In some embodiments, a process of active gripping may include feedbackfrom one or more sensors such as displacement sensors, force sensors,pressure sensors and so on that are associated with one or more fingersassociated with an active gripper. These sensors provide a measure ofhow much force is being applied by the one or more fingers. Thisfeedback may be used to prevent the application of excessive force bythe active gripper that may damage an object being gripped. In otherembodiments, mechanical force limiters (such as torsion springs or othercompliant members) may be used instead of feedback sensors to limit theforce being exerted by the gripper on an object being gripped.

FIG. 4 is a block diagram depicting an embodiment of an object grippingsystem 400. In some embodiments, object gripping system 400 includesrobotic actuator 102 mechanically coupled to gripper 104. In particularembodiments, robotic actuator 102 may be any one of a multi degree offreedom robotic arm, a gantry robot, a multi degree of freedom linearstage assembly, or some other robotic actuator.

In some embodiments, gripper 104 may be comprised of two or more fingerslocated around a central axis. Each finger may include one or more teethor tooth features configured to hook or engage around an edge rim of arange of thickness, where the edge rim is associated with an object. Insome embodiments, the edge rim may be perpendicular to the central axis.In other embodiments, the edge rim may be at some other angle to theedge axis.

In some embodiments, the two or more fingers may be positioned in pairssubstantially opposing each other, in a circular pattern. In particularembodiments, a force applied by one finger in an opposing group offingers is substantially opposite to a force or forces applied by anopposing finger or a group of fingers respectively. In some embodiments,the fingers may move independently of each other. In other embodiments,the motion of the fingers may be coupled. In some embodiments, allfingers may be moveable with respect to a rigid reference structure. Inother embodiments, one or more fingers may be fixed with respect to arigid reference structure while other fingers may be moveable withrespect to the rigid reference structure. In some embodiments, a fingermay be comprised of a single, substantially rigid member. In otherembodiments, a finger may be comprised of multiple links, where themultiple links on each finger are coupled by pivot points.

In some embodiments, a process of gripping an object by a gripper may becomprised of multiple states. In one state, referred to as a “freestate,” the fingers associated with the gripper are passively positionedby any combination of gravitational forces or passive compliant memberssuch as springs. In one embodiment, referred to as “passive gripping,”in the free state, the gripper is moved to a position where the fingersof the gripper are pushed open by the object, thereby engaging a rim onthe object with teeth or hooks on the finger. This method provides agreater degree of tolerance to error in the relative positioning betweenthe gripper and the object to be gripped. On the other hand, if one ormore actuators are used to move the fingers such that the fingers engagearound an object to be gripped, then the gripping method is referred toas “active gripping.”

In an active gripper design, the fingers are actively moved in thegripping direction, whereby the tooth features converge around theobject. All of the above discussion regarding tooth features and fingergeometry applies to the active case. In some embodiments, activegripping may not require a “locked state”, which is inherently achievedby the force of the actuator and the back-driveability of the mechanism.However, unlike passive gripping, in the case of active gripping, thegripper needs to either (a) incorporate in-line compliance to prevent itfrom crushing the object, or (b) incorporate sensors capable ofdetecting the grip engagement event and stopping the gripper. Compliancefor the passive gripper is achieved through independent fingers and theuse of passive motion during the gripping action. In-line compliance iscommonly employed by other robotic grippers, and may be achieved throughpneumatic pressure, integral springs, etc. In-line compliance isinherently limiting if it is always present. On the one hand, thecompliance must be sized to the object set, which means that a user mustchoose between handling heavy objects and fragile objects. Heavy objectsrequire high-stiffness compliance, otherwise the user risks dropping theobject. Fragile objects require low-stiffness compliance, otherwise theuser risks breaking the object. Compliance must be sized to the range ofsizes of objects the gripper must handle. For example, in the case of adishware handling robot where objects are relatively fragile and heavy,and the user desires to accommodate a large range of sizes, in-linecompliance would need to be locked out by a secondary device ormechanism.

Once an object to be gripped is engaged, the gripper moves away from theobject. This process may allow additional motion of the fingers. Whenthe fingers are finally constrained by the object so as to preventmotion, the object will be lifted by the gripper as the grippercontinues to move. When the object is lifted by the gripper, the weightof the object can further engage the fingers against the objectaccording to the geometry of the tooth or hook features and the geometryof the fingers. When an object is gripped and lifted, the fingers may belocked using one or more locking mechanisms such as a roller clutch andother locking mechanisms discussed herein.

Once the object is moved to the desired location, the gripper istransitioned to a “release” state. In the released state, the fingers ofthe gripper are actively moved in an opening direction, which forces thefingers open and disengages the teeth or hooks on the fingers with theobject rim. In one embodiment, the release state is on a continuum ofmotion for a single actuator, which is also positioning the componentsbetween the free and locked states. In another embodiment, the releasestate employs an additional actuator, which is moved independently or inaddition to the actuator used for locking/freeing. In yet anotherembodiment, the fingers of the gripper are forced open by driving thegripper against a secondary device, such as a fixture. In thisembodiment, the mechanism in the gripper only needs to have two states,locked and free. A design for such an embodiment could use a simplerelectromechanical device, such as an electromagnetic brake or clutch, asolenoid, a hydraulic/pneumatic piston, etc.

In some embodiments, object gripping system 400 may also include asensing system that 404 that receives inputs from robotic actuator 102and gripper 104. Sensing system 404 may be used to augment thefunctionality of gripper 104, or in the case of active gripping, sensingsystem 404 could be used as a way to detect the engagement state withthe object to be gripped, in order to halt the motion of the gripper104. Whether for passive or active gripping, sensing system 404 couldprovide a user with a confirmation that the object is present, and couldsupply information about the size and/or location of the object withrespect to gripper 104. Sensing system 404 could also measure thegripping force, the weight of the object, or the state of secondarymechanisms inside gripper 104.

In one embodiment, the teeth on gripper 104 are equipped with sensors(that are a part of sensing system 404) such that the pressure appliedto the object can be detected. Any combination of pressure-sensitivefilm, strain gauges and capacitive plates are possible ways to create asignal from pressure focused at one point, or in one tooth location.Such signals convert pressure to electrical signals that can be read inby a processing system (such as processing system 402) for analysis. Inanother embodiment, the tooth edge of a finger is compliant or movablewith respect to the rest of the finger. Through deformation on the toothside of the finger, the shape of the deformation can be inferred andtherefore the object engagement position on the finger determined.Again, strain sensing or capacitance sensing as a part of sensing system404 could detect this deformation, where strain sensing or capacitancesensing are mechanisms to measure displacement. Additionally, magnetichall-effect sensors, position encoders or contact switches could also beused to determine relative positions or displacements. In anotherembodiment, the positions of the fingers associated with gripper 104could be measured using rotary or linear encoders, or position sensorsthat are included in sensing system 404. Additional range sensors couldbe applied to gripper 104 in order to measure one or more distances fromgripper 104 to the object. If the object is known, with the combinationof the finger positions and distances to the object, one could infer thelocation of the object engagement points in each finger. Additionally,the range sensor(s) could be used to verify that the object is in theproper location, and that it is present.

In some embodiments, sensing system 404 may include an imaging systemsuch as a camera that might provide visual data to an associatedcomputer vision system to identify an object to be gripped or todetermine a position of a gripper relative to the object to be gripped.In general, sensing system 404 includes a functionality to detect apresence of an object relative to gripper 104, and to determine alocation of the object with respect to gripper 104.

In some embodiments, a combination of sensors included in sensing system404 as discussed herein may be used to detect whether an object grippedby gripper 104 moves relative to gripper 104 after the object has beengripped; such relative motion may indicate that the object is notsecurely gripped. A non-secure grip may be associated with a greaterrisk of the object being dropped. The functionality in sensing system404 to detect a non-secure grip is useful to reduce a risk of an objectbeing dropped. In particular embodiments, sensing system 404 may also beconfigured to determine whether gripper 104 has failed to grip theobject.

In some embodiments, sensing system 404 may be configured to detectwhether gripper 104 has properly released a gripped object at a locationwhere the gripped object is to be deposited. In particular embodiments,sensing system 404 may be configured to determine whether a grippedobject has been unintentionally released by gripper 104.

In some embodiments, object gripping system 400 includes a processingsystem 402 that performs computing functions, data analysis functions,data storage functions, and other functions as discussed herein. Inparticular embodiments, processing system 402 may be implemented byusing any combination of processors such as field-programmable gatearrays (FPGAs), digital signal processors (DSPs), microcontrollers, orany other similar processors. Other components of processing system 402are discussed herein.

During operation, processing system 402 commands robotic actuator 102 toposition gripper 104 in a vicinity of an object to be gripped. Theprocess of positioning gripper 104 may be based on feedback providedfrom robotic actuator 102 or gripper 104 to processing system 402 viasensing system 404. Feedback provided to processing system 402 fromsensing system 404 may include visual positioning data from an imagingsystem, data from position sensors, or any other kind of positioningdata. Once gripper 104 is appropriately positioned, gripper 104 iscommanded by processing system 402 to grip the object. Robotic actuator102 moves gripper 104 in a first direction, towards the object. Using apassive gripping process or an active gripping process, gripper 104grips the object. Force feedback sensors and position sensors associatedwith the fingers provide a measure of the displacement of the fingersand the strength of the grip. In some embodiments, processing system 402may provide commands to gripper 104 via robotic actuator 102 to grip theobject with an appropriate amount of force. Processing system 402 maythen command gripper 104 to lock the fingers associated with gripper104.

Processing system 402 then commands the combination of robotic actuator102 and gripper 104 to manipulate the object. In some embodiments,manipulating the object might involve moving the object from a firstlocation to a second location. In this case, the object is moved to asecond location using, for example, position feedback sensors thatinclude visual positioning data, displacement sensors (angular andlinear), rate sensors (angular and linear), and so on. At the secondlocation, processing system 402 commands gripper 104 via roboticactuator 102 to release the grip on the object, and the object isdeposited at the second location.

FIG. 5 is a block diagram depicting an embodiment of processing system402 capable of operating a robotic actuator and gripper configured togrip and manipulate objects. In some embodiments, processing system 402includes a communication manager 502 that is configured to managecommunication protocols and associated communication with externalperipheral devices as well as communication within other components inprocessing system 402. For example, communication manager 502 may beresponsible for generating and maintaining the interface betweenprocessing system 402 and sensing system 404. Communication manager 502may also manage communication between the different components withinprocessing system 402.

In some embodiments, processing system 402 includes a memory 504 that isconfigured to store data associated with object gripping system 400.Data stored in memory 504 may be temporary data or permanent data. Insome embodiments, memory 504 may be implemented using any combination ofhard drives, random access memory, read-only memory, flash memory, andso on. In particular embodiments, data stored in memory 504 may includepositioning data associated with a gripper, a robotic actuator, and anobject to be gripped, data associated with an imaging system, dataassociated with force sensors, data associated with position sensors,and so on.

Processing system 402 may also include a sensing system interface 506that is configured to interface with sensing system 404. Sensing systeminterface 506 may include, for example, an interface to receive imagingdata from any associated imaging device that may be a part of sensingsystem 404. Sensing system interface 506 may also include data buses ordata paths (e.g., serial data buses or parallel data buses) that receivesensor data from force sensors, position sensors, or other sensorsassociated with robotic actuator 102 or gripper 104.

In some embodiments, processing system 402 includes a computer visionsystem 514 that is configured to process imaging data to determine, forexample, a relative position between a gripper and an object to begripped. Computer vision system 514 may also be configured to performimage recognition functions to detect and identify an object to begripped based on visual data provided by an imaging system.

Processing system 402 may also include a processor 508 that may beconfigured to perform functions that may include generalized processingfunctions, arithmetic functions, and so on. Processor 508 may also beconfigured to perform three-dimensional geometric calculations and solvenavigation equations in order to determine relative positions,trajectories, and other motion-related and position-related parametersassociated with manipulating an object. Processor 508 may also beconfigured to maintain forces exerted by fingers associated with gripper104 below a predetermined threshold to prevent damaging or breaking anobject being gripped.

In some embodiments, processing system 402 includes a robotic actuatorcontroller 510 that is configured to output actuation commands torobotic actuator 102 and gripper 104. The commands output by roboticactuator controller 510 may include positioning commands, fingermovement commands, finger lock/unlock commands, and so on.

A user interface 512 may be included in processing system 402. In someembodiments, user interface 512 is configured to receive commands from auser or display information to the user. For example, commands receivedfrom a user may be basic on/off commands, and may include variableoperational speeds. Information displayed to a user by user interface512 may include, for example, system health information and diagnostics.User interface 512 may include interfaces to one or more switches orpush buttons, and may also include interfaces to touch-sensitive displayscreens.

FIG. 6 is a block diagram depicting an embodiment of a robotic actuator102. In some embodiments, robotic actuator 102 includes one or moreactuators 602 that may be any combination of electrical motors,pneumatic actuators, hydraulic actuators, and so on, configured togenerate motion in robotic actuator 102 or gripper 104. Robotic actuator102 may also include a gripper controller 604 that is configured toreceive commands from processing system 402 and relay these commands togripper 104. In some embodiments, gripper controller 604 may be anelectromechanical interface that transmits both electrical andmechanical signals from robotic actuator 102 to gripper 104.

FIG. 7 is a block diagram depicting an embodiment of a sensing system404. In some embodiments, sensing system 404 includes one or more loadsensors 702 configured to measure force, such as forces exerted by oneor more fingers on an object being gripped. An example of a load sensoris a load cell. Sensing system 404 may also include one or moredisplacement sensors 704 that are configured to measure any combinationof linear and angular displacements, including linear and angular rates.Displacement sensors 704 may be used to measure displacements of one ormore fingers in gripper 104, or to measure displacements of roboticactuator 102. An example of a displacement sensors is a strain gauge,while accelerometers and gyroscopes may be used to measure linear andangular accelerations respectively.

In some embodiments, sensing system 404 may include an imaging system706 that is configured to capture visual data associated with roboticactuator 102, gripper 104, and an object to be gripped. Imaging system706 may be implemented using a camera system, for example. Outputs fromimaging system 706 may be used by processing system 402 to determine,for example, spatial positioning coordinates associated with roboticactuator 102, gripper 104, and an object to be gripped. Outputs fromimaging system 706 may also be processed by image recognition algorithmsrunning on processing system 402 to detect and identify one or moreobjects to be gripped.

FIG. 8A is a schematic diagram depicting a sequence of operations 800associated with gripping an object by an embodiment of a gripper such asgripper 104. In some embodiments, gripper 104 includes a first finger804 and a second finger 806, where first finger 804 is mechanicallycoupled to second finger 806 via a mechanical coupling 802. First finger804 and second finger 806 are each shown to have a plurality of teeth,for example a tooth 814 is associated with finger 804, and tooth 816 isassociated with finger 806. In some embodiments, mechanical coupling 802may include any combination of rigid support structures, springs,locking mechanisms (e.g., mechanical clutches such as roller clutches),and other mechanical coupling devices as discussed herein. In someembodiments, mechanical coupling 802 serves to hold each of finger 804and finger 806 in an equilibrium position as discussed herein.

In some embodiments, gripper 104 may be commanded by processing system402 to grip an object—in this case an object 808—resting on a worksurface 810. To grip object 808, gripper 104 moves in a first direction812 towards object 808, from an initial position where there is nophysical contact between any part of gripper 104 and object 808. Gripper104 may be moved in first direction 812 via robotic actuator 102. Thedescription of the sequence of operations 800 associated with grippingobject 808 continues in the description of FIG. 8B.

FIG. 8B is a continued description of the sequence of operations 800associated with gripping an object by gripper 104. Gripper 104 continuesmoving in first direction 812 towards object 808 on work surface 810, tothe point where each of finger 804 and finger 806 touches object 808 asshown in FIG. 8B. Mechanical coupling 802 continues to hold each offinger 804 and finger 806 in an equilibrium position. The description ofthe sequence of operations 800 associated with gripping object 808continues in the description of FIG. 8C.

FIG. 8C is a continued description of the sequence of operations 800associated with gripping an object by gripper 104. Gripper 104 continuesmoving in first direction 812. Since each of finger 804 and finger 806are in physical contact with object 808 on work surface 810, each offinger 804 and finger 806 are pushed apart from each other (i.e., finger804 and finger 806 move apart from each other) due to a combination ofphysical forces exerted on each of finger 804 and finger 806 by object808 and a physical constraint associated with object 808. Mechanicalcoupling 802 accordingly adjusts to the combined motion of finger 804and finger 806 via compression or extension motion in one or more springmechanisms associated with mechanical coupling 802, as discussed herein.In some embodiments, finger 804 and finger 806 move apart againstmechanical spring tension in mechanical coupling 802. The description ofthe sequence of operations 800 associated with gripping object 808continues in the description of FIG. 8D.

FIG. 8D is a continued description of the sequence of operations 800associated with gripping an object by gripper 104. Gripper 104 continuesmoving in first direction 812, and finger 804 and finger 806 continue tobe forced apart due to mechanical interaction with object 808 on worksurface 810. FIG. 8D shows a point where a tip of tooth 814 and a tip oftooth 816 each makes contact with an edge 818 of object 808. Thedescription of the sequence of operations 800 associated with grippingobject 808 continues in the description of FIG. 8E.

FIG. 8E is a continued description of the sequence of operations 800associated with gripping an object by gripper 104. Gripper 104 continuesmoving in first direction 812, and due to forces (such as springtension) generated in mechanical coupling 802, finger 804 and finger 806may close slightly such that edge 818 of object 808 on work surface 810is gripped by a combination of finger 814 and finger 816. In someembodiments, this gripping process is achieved by a combination offorces generated between object 808, tooth 814, and tooth 816, andforces (such as spring tension forces) generated by mechanical coupling802. At this time, mechanical coupling 802 may be locked by commandsfrom processing system 402 to prevent any further motion of finger 804or finger 806. The description of the sequence of operations 800associated with gripping object 808 continues in the description of FIG.8F.

FIG. 8F is a continued description of the sequence of operations 800associated with gripping an object by gripper 104. Once object 808 hasbeen gripped by tooth 814 and tooth 816, processing system 102 maycommand gripper 104 to move in a second direction 820 that issubstantially opposite to first direction 812. Since object 808 isgripped and locked, object 808 is lifted above work surface 810 by acombination of finger 814 and finger 816. FIG. 8F also shows mechanicalcoupling 802 in a locked state. In some embodiments, the weight ofobject 808 serves to enhance the grip (i.e., the gripping forces)exerted by gripper 104 on object 808.

In some embodiments, any spring mechanisms associated with mechanicalcoupling 802 (for example, spring 224 associated with passive gripper200) serve to increase a rate (or speed) at which object 808 is grippedby gripper 104 relative to an embodiment that does not use any springmechanism. In an absence of any spring mechanism associated withmechanical coupling 802, either or both of finger 814 or finger 816might slide off (or “bounce” off) object 808 rather than engaging withobject 808 during a gripping process. Such occurrences may also beobserved during operation of an active gripper (such as active gripper300) if the associated teeth are driven (or moved) too quickly byactuators such as pneumatic actuator 312. Including one or more springmechanisms in mechanical coupling 802 prevents such missed grippingattempts, thereby increasing operation speed of gripper 104 whileallowing an active gripper to be driven faster relative to a grippingspeed achievable in the absence of any spring mechanism.

FIG. 9A is a flow diagram depicting an embodiment of a method 900 forgripping an object by a passive gripper. At 902, a processing system(such as processing system 402) in conjunction with a sensing system(such as sensing system 404) identifies, at a first location on a worksurface (such as work surface 112), an object to be gripped. In someembodiments, the object to be gripped is an object such as object 110.At 904, the processing system commands a robotic actuator (such asrobotic actuator 102) to move a gripper (such as gripper 104) associatedwith the robotic actuator to a vicinity of the object. Next, at 906, theprocessing system commands the robotic actuator to move the gripper in afirst direction so that the gripper makes contact with the object. Thisstep is similar to the scenario depicted in FIG. 8B. At 908, theprocessing system commands the gripper to continue moving in the firstdirection which causes one or more teeth in two or more fingersassociated with the gripper to mechanically engage and grip the object.This step is similar to the sequence of events depicted in FIGS. 8C, 8D,and 8E. In some embodiments, a physical interaction between the gripperand the object causes the one or more fingers to be moved apart or asdescribed herein. In particular embodiments, the one or more fingers arepushed apart against spring tension. At 910, the method checks todetermine whether the object is gripped. In some embodiments, this checkis performed by processing system 402 responsive to inputs from sensingsystem 404. The inputs provided to processing system 402 by sensingsystem 404 may include data from any combination of sensors such aspressure sensors, force sensors, displacement sensors, and other sensorsas described herein. If the object is not gripped, the method returns to908. If the object is gripped, the method goes to A, with a continueddescription in FIG. 9B.

FIG. 9B is a continued description of method 900. Starting at A, themethod goes to 912, where the processing system initiates a command tolock the gripper. In some embodiments, the process of locking thegripper can be interpreted as a transition from a free state (where thefingers are able to move under the influence of external forces) to alocked state, where any motion of the fingers is substantiallyconstrained by one or more locking mechanisms. In some embodiments, alocking mechanism is configured to lock the fingers of the gripper,preventing movement of at least one of the fingers in at least onedirection. In one particular embodiment, the locking mechanism isconfigured to lock each finger associated with the gripper independentlyof other fingers associated with the gripper. In another embodiment, thelocking mechanism simultaneously locks all fingers associated with thegripper.

In a locked state, the fingers are prevented from moving in at least onedirection, through the use of a locking mechanism. For example, in onedesign, a brake pad surface is forced against a surface on one or morefingers. In this case, the brake pad and fingers can be designed suchthat engagement of the braking surface can be applied on multiplefingers at the same time with a single brake part, where each finger isat a different position within its range of motion, and the fingers moveindependently. In the brake-pad design, motion on each finger isresisted in both directions by the friction of the braking element. Itis preferable in such a design to position the brake pad surface suchthat it is self-locking, meaning the applied loads from the dish objectto the finger tooth feature cause additional clamping force in thebrake, which increases its holding force.

Alternate designs could position the braking elements such that they areprone to separation, which reduces braking force. In another embodimentof the brake-pad design, the braking surfaces are toothed in order toincrease holding force. A further embodiment would be the use ofratcheting teeth, such that motion in one direction is allowed, whereasin the other direction it is restricted.

In another design, the motion of the fingers can be restricted throughthe use of a roller clutch component, whereby a cylindrical device iswedged between a cylindrical feature coupled to the finger and areference surface. Such a cylindrical device prevents rotation of thefinger in one direction, but allows rotation in the other, through awedging effect. A roller clutch (or some other locking mechanism) can beused to simultaneously lock all fingers, with each finger possibly beingat a different location in its travel. The roller clutch designoptionally may employ the use of one or more springs to force the wedgeroller in the wedging direction. There may also be a retention featureon a lower reference surface, which keeps the roller contained in themechanism when it is not wedged against the finger cylindrical surface.The reference surface, which the roller wedges against, may be moveablerelative to other reference surfaces. This would allow the mechanism toovercome any compressibility in the components that might otherwise keepthe device in the locked state. In the brake-pad embodiment, locking isdefined by contact or lack-thereof between adjacent brake surfaces.Compressibility within the materials of the brake-pads, or in themechanism itself, provides a tolerance range for which the mechanism isbetween a locked state and a free state. If the mechanism is at maximumbraking force at position x and completely free at position y, betweenposition x and position y, there will be variable braking force.However, in the roller-clutch design, the mechanism has more of a binarystate. The mechanism is locked at any position less than a specifiedposition z that may be determined as a design parameter, and is free atany position greater than z, assuming the component materials have beenselected to minimize compression (this is preferred).

With the gripper in a locked state, the object can be moved quickly andwith fewer constraints. In an unlocked gripper, which is designed to becapable of passive gripping as described herein, the finger mechanismsmay have motion coupling, which would allow the object to move relativeto the fixed parts of the gripper when the object is gripped. Thisbehavior is undesirable if the object is to be moved quickly, or if auser wishes to reorient the object with respect to gravity. Locking thefingers as described overcomes this shortcoming. In the case of activegripping, coupling between the fingers might be avoided, and thereforelocking the fingers could be unnecessary. Once the object is moved tothe desired location, the gripper is transitioned to a “released” state.In the released state, the fingers of the gripper are actively moved inan opening direction, which forces the fingers open and disengages theteeth or hooks on the fingers with the object rim (or edge). In oneembodiment, the release state is on a continuum of motion for a singleactuator, which is also positioning the components between the free andlocked states.

In another embodiment, the release state employs an additional actuator,which is moved independently or in addition to the actuator used forlocking/freeing. In yet another embodiment, the fingers of the gripperare forced open by driving the gripper against a secondary device, suchas a fixture. In this embodiment, the mechanism in the gripper onlyneeds to have two states, locked and free. A design for such anembodiment could use a simpler electromechanical device, such as anelectromagnetic brake or clutch, a solenoid, a hydraulic/pneumaticpiston, etc. Alternatively, the previous discussion of a three-stategripper requires more accurate position control, particularly of therelease motion. In a two-state gripper, position control of the releaseis achieved by the positioning system.

Returning back to the description of FIG. 9B, at 914, the method checksto if the gripper is locked. This function may be accomplished viafeedback from the locking mechanism to the processing system. If at 914the method 900 determines that the gripper is not locked, then themethod returns back to 912. If at 914 the method determines that thegripper is locked, then the method goes to 916, where the processingsystem commands the robotic actuator to move the gripper in a seconddirection that is substantially opposite to the first direction whichlifts the object off the work surface. In some embodiments, the seconddirection is similar to second direction 820. Next, at 918, theprocessing system commands the robotic actuator to move the gripper to asecond location. This movement of the object may correspond tomanipulating the object by the gripper. In some embodiments, other kindsof object manipulation methods (such as reorienting the object inthree-dimensional space) may be implemented instead of or in addition tomoving the object to a second location. At 920, the processing systemcommands the gripper to set the object down at the second location, andat 922, the processing system commands the gripper to release the objectat the second location. This completes the process of gripping theobject, moving the object from the first location to the secondlocation, and depositing the object at the second location via passivegripping.

FIG. 10A is a flow diagram depicting an embodiment of a method 1000 forgripping an object by an active gripper. At 1002, a processing system(such as processing system 402) in conjunction with a sensing system(such as sensing system 404) identifies, at a first location on a worksurface (such as work surface 112), an object to be gripped. In someembodiments, the object to be gripped is an object such as object 110.At 1004, the processing system commands a robotic actuator (such asrobotic actuator 102) to move a gripper (such as gripper 104) associatedwith the robotic actuator to a vicinity of the object. Next, at 1006,the processing system issues commands to move one or more fingers of thegripper so that the one or more fingers wrap around the object and oneor more teeth in the one or more fingers mechanically engage and gripthe object. In some embodiments, the process of moving one or morefingers of the gripper is the process of active gripping, where the oneor more fingers may each be moved using an actuator such as a pneumaticactuator. At 1008, the method checks to determine whether the object isgripped. In some embodiments, this check is performed by processingsystem 402 responsive to inputs from sensing system 404. The inputsprovided to processing system 402 by sensing system 404 may include datafrom any combination of sensors such as pressure sensors, force sensors,displacement sensors, and other sensors as described herein. If theobject is not gripped, the method returns to 1006. If the object isgripped, the method goes to A, with a continued description in FIG. 10B.

FIG. 10B is a continued description of method 1000. Starting at A, themethod 1000 goes to 1010, where the processing system initiates acommand to lock the gripper. In some embodiments, the process of lockingthe gripper can be interpreted as a transition from a free state (wherethe fingers are able to move under the influence of external forces) toa locked state (where any motion of the fingers is substantiallyconstrained by one or more locking mechanisms).

At 1012, the method 1000 checks to see if the gripper is locked. Thisfunction may be accomplished via feedback from the locking mechanism tothe processing system. If at 1012 the method determines that the gripperis not locked, then the method returns to 1010. If at 1012 the methoddetermines that the gripper is locked, then the method goes to 1014,where the processing system commands the robotic actuator to move thegripper in a second direction that is substantially opposite to thefirst direction which lifts the object off the work surface. In someembodiments, the second direction is similar to second direction 820.Next, at 1016, the processing system commands the robotic actuator tomove the gripper to a second location. This movement of the object maycorrespond to manipulating the object by the gripper. In someembodiments, other kinds of object manipulation methods may beimplemented instead of or in addition to moving the object to a secondlocation. At 1018, the processing system commands the gripper to set theobject down at the second location, and at 1020, the processing systemcommands the gripper to release the object at the second location. Thiscompletes the process of gripping the object, moving the object from thefirst location to the second location, and depositing the object at thesecond location via active gripping.

While various embodiments of the present disclosure are describedherein, it should be understood that they are presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the disclosure.Thus, the breadth and scope of the present disclosure should not belimited by any of the described exemplary embodiments, but should bedefined only in accordance with the following claims and theirequivalents. The description herein is presented for the purposes ofillustration and description. It is not intended to be exhaustive or tolimit the disclosure to the precise form disclosed. Many modificationsand variations are possible in light of the disclosed teaching. Further,it should be noted that any or all of the alternate implementationsdiscussed herein may be used in any combination desired to formadditional hybrid implementations of the disclosure.

1. An apparatus comprising: a first finger that includes a plurality ofteeth; and a second finger mechanically coupled to the first finger,wherein the second finger includes a plurality of teeth, wherein thefirst finger and the second finger are configured to move apart when thefirst finger and the second finger are moved in a first directionagainst an object, and wherein the first finger and the second fingerare configured to grip the object when the first finger and the secondfinger are moved in a second direction that is substantially opposite tothe first direction.
 2. The apparatus of claim 1, wherein the firstfinger and the second finger are configured to move independently ofeach other.
 3. The apparatus of claim 1, wherein the first finger andthe second finger are each configured to move via a mechanical coupling,and wherein the movement of the first finger and the second fingerincludes the first finger and the second finger moving collectively. 4.The apparatus of claim 1, wherein the first finger and the second fingerare each configured to move passively, wherein the passive movement isinitiated by gravity, contact of the first finger or the second fingerwith the object, or at least one spring mechanism.
 5. The apparatus ofclaim 1, wherein the first finger and the second finger are eachconfigured to move actively, wherein the active movement is controlledby an actuator.
 6. The apparatus of claim 1, further comprising alocking mechanism configured to lock the first finger or the secondfinger by preventing movement of the first finger or the second fingerin at least one direction.
 7. The apparatus of claim 6, wherein thelocking mechanism is configured to lock the first finger or the secondfinger independently of the second finger or the first fingerrespectively.
 8. The apparatus of claim 6, wherein the locking mechanismis a roller clutch configured to simultaneously lock the first fingerand the second finger.
 9. The apparatus of claim 1, further comprising aspring mechanism coupled to at least one of the first finger or thesecond finger.
 10. The apparatus of claim 9, wherein the springmechanism is configured to increase a speed of gripping the objectrelative to a speed of gripping the object in an absence of the springmechanism.
 11. The apparatus of claim 1, wherein each of the firstfinger and the second finger further comprises multiple links, whereinthe multiple links are coupled by pivot points.
 12. The apparatus ofclaim 1, wherein the object is an article of dishware.
 13. The apparatusof claim 1, wherein at least one of the first finger or the secondfinger is removable independently of the other finger.
 14. The apparatusof claim 1, wherein the object is gripped by engagement of the object byat least one tooth of the first finger and at least one tooth of thesecond finger.
 15. The apparatus of claim 1, further comprising asensing system configured to determine a position of the object relativeto a position of the first finger or the second finger.
 16. Theapparatus of claim 15, wherein the sensing system is further configuredto detect whether the gripped object moves relative to either the firstfinger or the second finger.
 17. The apparatus of claim 1, furthercomprising at least one sensor configured to measure at least one offorce, displacement, pressure, or position associated with the firstfinger or the second finger.
 18. The apparatus of claim 17, wherein datafrom the at least one sensor is used to limit a force exerted on theobject by the first finger or the second finger.
 19. The apparatus ofclaim 1, further comprising a computer vision system configured toprocess visual data from an imaging system to detect and identify anobject to be gripped.
 20. The apparatus of claim 19, wherein thecomputer vision system determines a position of the object relative tothe first finger and the second finger.
 21. A method comprising:identifying, by a processing system, an object to be gripped at a firstlocation; commanding, by the processing system, a robotic actuator tomove a gripper in a first direction so that the gripper makes contactwith the object, wherein one or more teeth in a plurality of fingersassociated with the gripper mechanically engage the object; andcommanding, by the proceeding system, the robotic actuator to move thegripper in a second direction that is substantially opposite to thefirst direction, causing the gripper to grip the object.
 22. The methodof claim 21, wherein each of the plurality of fingers movesindependently of the other fingers.
 23. The method of claim 21, whereinthe plurality of fingers move collectively.
 24. The method of claim 21,wherein each of the plurality of fingers is configured to move passivelybased on gravity, contact of the first finger or the second finger withthe object, or a spring mechanism.
 25. The method of claim 21, whereineach of the plurality of fingers is configured to move actively, whereinthe active movement is controlled by an actuator.